Cam wheel mechanism for watches

ABSTRACT

An cam wheel mechanism adapted for application to stopwatch or chronograph arrangements in watches is provided having a ratchet wheel superposed on and tightly fixed to a cam wheel for rotation about a common axis. An operating lever is positioned for engagement with a tooth of the ratchet wheel for the incremental rotation of said ratchet wheel and cam wheel. The cam wheel is formed with alternating projections and recesses in the periphery thereof dimensioned for engagement or receipt of a corresponding projection on a start and stop lever biased against said cam wheel. The projection on the start and stop lever, and the projections and recesses on said cam wheel cooperating to position the start and stop lever and the cam wheel between operative displacements of said operating lever without the use of a cam wheel spring.

United States Patent [191 Morita [s41 CAM WHEEL MECHANISM FOR WATCHES [75 1 Inventor: Katsuhiko Morita, Tokyo, Japan 751' "Xssigne? Kabuiihilri Kaislia partisan-m Koto-Ku, Tokyo, Japan [21] Appl. No.: 75,028

[30] Foreign Application Priority Data [451 Jan.23, 1973 9/1952 Switzerland ..58/74 4/1956 Switzerland ..58/74 [57] ABSTRACT An cam wheel mechanism adapted for application to stopwatch or chronograph arrangements in watches is provided having a ratchet wheel superposed on and tightly fixed to a cam wheel for rotation about a common axis, An operating lever is positioned for engagement with a tooth of the ratchet wheel for the incremental rotation of said ratchet wheel and cam wheel. The cam wheel is formed with alternating projections and recesses in the periphery thereof dimensioned for engagement or receipt of a corresponding projection on a start and stop lever biased against said cam wheel. The projection on the start and stop lever, and the projections and recesses on said cam wheel cooperating to position the start and stop lever and the cam wheel between operative displacements of said operating lever without the use of a cam wheel spring.

5 Claims, 3 Drawing Figures PATENTEDJANZB ms I N VEN TOR.

K4715 (/H/KU pg 74 CAM WHEEL MECHANISM FOR WATCHES BACKGROUND OF THE INVENTION This invention relates to a cam wheel mechanism particularly adapted for application to stopwatch or chronograph mechanisms. In particular, the invention relates to a cam wheel adapted to control a start and stop lever without the use ofa cam wheel spring.

In conventional stopwatch or chronograph constructions, a push button is provided extending to the outside of the watch case, and operatively coupled with an operating lever, for the slidable displacement of said operating lever when said push button is pushed. The inner end of said operating lever engages with a ratchet formed at the periphery of a column wheel. Pushing said push button serves to index the ratchet by one pitch, said ratchet then being positioned by a separate column wheel spring.

Said prior art column wheel is also provided with a plurality of columns projecting in substantially parallel relation from one face thereof. Each of said columns is radially spaced from the axis of rotation of the column wheel and circumferentially spaced from the other of said columns. A start and stop lever is provided positioned so that when one end thereof engages the side surface of one of the columns, the other end thereof engages the side surface of the balance wheel, in the case of a stopwatch, or operates the clutch mechanism of a chronograph. This arrangement serves to stop the oscillation of the balance wheel or to operate the clutch of a chronograph to cut off said chronograph. When the firstmentioned end of said start and stop lever is positioned in the hollow between two of said columns, said other end of said lever is disengagedfrom the balance wheel or chronograph clutch, whereby said balance wheel is permitted to oscillate, or the clutch of the chronograph is connected. By depressing the push button the start and stop lever is alternately positioned in each of the two above-described states.

The foregoing column wheel arrangement is extremely delicate and it is difficult to adjust the relative positional relationship between the operating lever, the start and stop lever, the column wheel spring and the column wheel. A further disadvantage of the abovedescribed column wheel mechanism is that the column wheel spring tends to break due to the strong force required to position the column wheel.

SUMMARY OF THE INVENTION Generally speaking, in accordance with the invention, a cam wheel mechanism for a stopwatch or chronograph is provided including a watch case, a push button projecting outside of said watch case, an operating lever positioned within said watch case for operative displacement by said push button, a ratchet wheel having a plurality of teeth, a cam wheel formed with a plurality of alternating radially extending projections and recesses in the periphery thereof, said cam wheel being superposed on and fixed to said ratchet wheel for rotation about a common axis, said ratchet wheel and cam wheel being positioned within said watch case with said ratchet teeth in the path of displacement of said operating lever for incremental rotation of said ratchet wheel and cam wheel in response to the displacement of said operating lever, and a start and stop lever pivotably mounted within said watch case and formed with a projection positioned and dimensioned for alternate engagement against said cam wheel projections and receipt within said cam wheel recesses for pivotably positioning said start and stop lever and for retaining said cam wheel and ratchet wheel between operative displacements of said operating lever. Said start and stop lever is biased against said cam wheel and serves to control the operation of other watch parts without the provision ofa cam wheel spring.

Accordingly, it is an object of this invention to provide a cam wheel mechanism for stop watches or chronograph which do not require the provision of a cam wheel spring.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a top plan view ofa portion of a watch construction incorporating the cam wheel mechanism according to the invention, the start and stop lever thereof being out of engagement with the balance wheel;

FIG. 2 is a top plan view of the embodiment of FIG. 1, the start and stop lever being positioned to stop the balance wheel; and

FIG. 3 is a fragmentary top plan view of the cam wheel mechanism according to the invention as applied to a hand return mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, the cam wheel construction according to the invention includes a push button 2 mounted on a watchcase 1. An operating lever 3 having a elongated narrow slot 3a is mounted within said watchcase. Specifically, a pin 5 projecting perpendicularly from a frame plate 4 is received within slot 3a. End 3c of operating lever 3 is positioned in close proximity to the bottom of push button 2 due to the biasing force of operating lever spring 6 which engages a pin 3b mounted on said operating lever. Operating lever 6 is formed with two apertures therethrough in the region thereof spaced from said operating lever, one of said openings being dimensioned to receive a pin 7 projecting perpendicularly from frame plate 4, the other of said openings receiving a screw 8 which secures said operating lever spring to said frame plate.

A ratchet wheel 9 having a plurality of teeth, for example eight teeth, is positioned in the path of the end 3d of operating lever 3. A cam wheel 10 having a plurality of projections 10a alternating with a plurality of recesses 10b is superposed on and tightly fixed to ratchet wheel 9 for rotation about a common axis 19 mounted on frame plate 4. Cam wheel 10 has, for example, four projections and four recesses.

A start and stop lever 11 is pivotably mounted to frame plate 4 by means of a focrum l2. Said start and stop lever is biased against cam wheel 10 by means of a start and stop lever spring 13, which is also formed with two openings in a region thereof spaced from said start and stop lever. One of said openings is inserted in a pin 14 extending perpendicularly from frame plate 4, the other of said openings receiving a screw 15 securing said start and stop lever spring to said frame plate. This method of mounting the springs of the construction according to the invention serves to substantially lessen the time for assembling and disassembling the components thereof.

Start and stop lever 11 is formed with a projection 11a positioned and dimensioned for receipt within the recesses 10b, as shown in FIG. 1, or engagement against projections 10a. When disposed in either of said positions, projection 11a serves to retain and position the assembly of said cam wheel and ratchet wheel between displacement of operating lever 3. Thus, the frictional engagement between projection 11a and projection 10a is sufficient to retain said cam wheel and ratchet wheel assembly in position, despite the application of shocks to the watch.

Frame plate 4 is formed with a cut-out region 4a, a pin 16 being mounted at the end of start and stop lever 11 so as to project through said cut'out portion toward the inside of the watch movement. In the embodiment of FIGS. 1 and 2, the pin 16 serves to start or stop the balance wheel 17 by engaging against the side surface thereof. A fixing pin 18 extends perpendicularly from frame plate 4 for the purpose of limiting the range of movement of lever 11.

In the stage shown in FIG. 1, the projection 11a engages with the projection 10a of cam wheel 10, so that pin 16 is out of engagement with balance wheel 17, and said balance wheel may freely operate. When push button 2 is pushed once, operating lever 3 is displaced against the resistance of spring 6, pin 5 acting as a guide. The displacement of operating lever 3 is applied to one tooth of ratchet wheel 9 to rotate the assembly of said ratchet wheel and cam wheel by an incremental distance which is, in this embodiment, equal to one pitch of ratchet wheel 9. Projection 11a rides along the peripheral surface of cam wheel 10, coming to rest within a recess b, resulting in the pivotable displacement of start and stop lever 1 l in the counter clockwise direction, as viewed in FIGS. 1 and 2. Said pivotable displacement, caused by the biasing of spring 13 is stopped by fixing pin 18, at which position pin 16 engages against the side surface of balance wheel 17, and the oscillation of the balance wheel is stopped. When the operator of the watch releases his finger from push button 2, said push button automatically returns to the original position due to the spring action of operating lever spring 6.

When push button 2 is pushed once again, ratchet wheel 9 is incrementally rotated by another pitch, in the manner described above, so that projection 11a engages with a projection 10a of cam wheel 10 to position said start and stop lever as shown in FIG. 1, whereby the balance wheel is restarted due to the frictional engagement between pin 16 and the side surface of said balance wheel during the disengagement thereof.

While in the embodiment of FIGS. 1 and 2, start and stop lever 11 serves to control the operation of a balance wheel, said start and stop lever may operate other mechanisms of the watch, if desired. Thus, said lever may operate the clutch of a chronograph (not shown). In still another embodiment shown in FIG. 3,-

the cam wheel mechanism according to the invention is reference numerals 3', 5, 6', 9' and 20' are applied to components which correspond to like components in the embodiment of FIGS. 1 and 2. In the embodiment of FIG. 3, a hammer 20 is pivotably mounted on the frame plate by means of a focrum 21, and is formed with a projection 20a. Projection 20a is engaged against cam wheel 10 by hammer spring 22, which is secured to the frame plate in the manner described above in connection with spring 13. A heart-shaped cam 23 would be mounted within the watch case and fixed to the second hand axis.

When projection 20a is engaged with a projection on cam wheel 10', the second hand is freely rotatable. When the projection 20a is received within a recess in said cam wheel, the end 20b of hammer 20 engages against the side surface of heart-shaped came 23 to position said heart-shaped cam as shown in FIG. 3. In other words, the engagement of hammer 20 against the heart-shaped cam returns the second hand to the zero position by displacing the cam until said cam comes to rest with the recess portion thereof engaging end 20b of hammer 20.

Thus, in accordance with the invention, a device actuating lever coupled with a cam wheel may be provided for application with any of a number of watch devices, such as the balance wheel, a clutch mechanism, or a hand return mechanism.

I claim:

1. A cam wheel mechanism for the selective operation of watch devices comprising a watch case; a push button projecting outside of said watch case; an operating lever positioned within said watch case for operative displacement by said push button; a ratchet wheel having a plurality of teeth; a cam wheel formed with a plurality of alternating radially extending projections and recesses in. the periphery thereof, said cam wheel being superposed on and fixed to said ratchet wheel for rotation about a common axis, said ratchet wheel and cam wheel being positioned within said watch case with said ratchet wheel in the path of displacement of said operating lever for the incremental rotation of said ratchet wheel and cam wheel in response to the displacement of said operating lever; a device actuating lever pivotably mounted within said watch case and formed with a projection positioned for alternate engagement against said cam wheel projection and receipt within said cam wheel recesses, said device actuating lever projection and cam wheel being correspondingly dimensioned for the pivotable positioning of said device actuating lever and for retaining said cam wheel and ratchet wheel between operative displacements of said operating lever without the use ofa spring detent engaging said cam wheel; and spring means for biasing said device actuating lever against said cam wheel, said device actuating lever being positioned for operative cooperation with said watch device in response to the pivotable displacement of said device actuating ver in response to the displacement of said push button.

2. A cam wheel mechanism as recited in claim 1, wherein said device actuating lever is a start and stop lever, said watch device including a balance wheel mounted within said watch case for engagement by said start and stop lever at one of the two pivotable positions thereof, said start and stop lever being out of engagement with said balance wheel at the other of its two pivotable positions.

said heart-shaped cam being positioned for engagement by said hammer at one of the two pivotal positions thereof for rotatably positioning said heartshaped cam and shaft.

5. A cam wheel mechanism as recited in claim 1, wherein said operating lever is formed with an elongated slot opening therein, said cam wheel mechanism including a pin fixedly mounted within said watch case and extending through said slot opening for guiding said operating lever during the displacement thereof. 

1. A cam wheel mechanism for the selective operation of watch devices comprising a watch case; a push button projecting outside of said watch case; an operating lever positioned within said watch case for operative displacement by said push button; a ratchet wheel having a plurality of teeth; a cam wheel formed with a plurality of alternating radially extending projections and recesses in the periphery thereof, said cam wheel being superposed on and fixed to said ratchet wheel for rotation about a common axis, said ratchet wheel and cam wheel being positioned within said watch case with said ratchet wheel in the path of displacement of said operating lever for the incremental rotation of said ratchet wheel and cam wheel in response to the displacement of said operating lever; a device actuating lever pivotably mounted within said watch case and formed with a projection positioned for alternate engagement against said cam wheel projection and receipt within said cam wheel recesses, said device actuating lever projection and cam wheel being correspondingly dimensioned for the pivotable positioning of said device actuating lever and for retaining said cam wheel and ratchet wheel between operative displacements of said operating lever without the use of a spring detent engaging said cam wheel; and spring means for biasing said device actuating lever against said cam wheel, said device actuating lever being positioned for operative cooperation with said watch device in response to the pivotable displacement of said device actuating lever in response to the displacement of said push button.
 2. A cam wheel mechanism as recited in claim 1, wherein said device actuating lever is a start and stop lever, said watch device including a balance wheel mounted within said watch case for engagement by said start and stop lever at one of the two pivotable positions thereof, said start and stop lever being out of engagement with said balance wheel at the other of its two pivotable positions.
 3. A cam wheel mechanism as recited in claim 1, wherein said device actuating lever being a start and stop lever, said watch device being clutch means positioned for engagement by said start and stop lever at a first of the two pivotable positions thereof, and for disengagement at a second of the two pivotable positions thereof.
 4. A cam wheel mechanism as recited in claim 1, wherein said device actuating lever is a hammer, said watch device including hand return means having a shaft, and a heart-shaped cam mounted on said shaft, said heart-shaped cam being positioned for engagement by said hammer at one of the two pivotal positions thereof for rotatably positioning said heart-shaped cam and shaft.
 5. A cam wheel mechanism as recited in claim 1, wherein said operating lever is formed with an elongated slot opening therein, said cam wheel mechanism including a pin fixedly mounted within said watch case and extending through said slot opening for guiding said operating lever during the displacement thereof. 